AN INVESTIGATION INTO THE GEOTECHNICAL PROPERTIES OF SOIL IN FOBUR AREA OF JOS-PLATEAU, NIGERIA.

This study deals with characterization of soil within Fobur area which covers six major locations. Undisturbed soil samples were collected at each of the locations of the six stations within the study area and the properties tested. The five sets of soil samples obtained from each of the 1.5m depth sample pit were grouped under American Association of State Highway and Transportation Officials (AASHTO). Other properties such as California Bering Ratio (CBR), Atterberg limit, particle size distribution, compaction test, and triaxial test were conducted. Engineering properties and mineralogy of the soil from the six (6) identified points were analyzed. The CBR values range from 32.1% to 81.6%, with the highest values observed at depths of 0.30–0.60 meters in Point A (81.6%) and Point E (76.3%). The shear strength values range from 10.5 KN/m² to 26.5 kN/m², with the highest values observed at Point B (26.5 kN/m²) and Point F (26.0 kN/m²). OMC values range from 8.1% to 12.0%, with the highest values observed at Point B (12.0%) and Point C (11.2%). The MDD values range from 1.81 mg/m³ to 2.16 Mg/m³, the natural moisture content (NMC) values range from 0.57% to 9.00%, the specific gravity values range from 2.13 to 2.95. The Plasticity Index (PI) range from 7.6% to 30.9%, with the highest values observed at Point B (30.9%) and Point D (22.0%). The eastern sectors as high-risk zones due to low CBR (<40%) and elevated plasticity, while western regions exhibited more favorable conditions. Recommendations were made to improve the defective soil for infrastructural development.